OK ... back to the topic. In cases like the one in question at the original post, I generally like to simplify the situation down to a little diagram or two. Think about the circuit(s) involved; the voltages, currents, and resistances - and what sort (magnitude) of values they are likely to be.
And then, with "active" kit like ESU's, think for a moment about the power being dished out, its frequency and wave-shape(s), and its duration ... then ask yourself questions like:- "where does all that energy go" (where is it dissipated), and - importantly - what good does it do (as far as the patient is concerned)?
Such an approach works when thinking about all kinds of kit; ESU's, defibs, x-ray, active physio stuff ... you name it.
Lastly (let's hope), in the case of two ESU's acting on the same body mass, I would suggest that each ESU effectively has its own little circuit:- ESU -> active electrode -> body -> return plate -> back to the ESU. In a carefully (properly) arranged set-up, any interaction between the two ESU's is going to be negligible (if any), I would have thought.
In fact it would be interesting to find out how close each pair of active electrodes and return plates would need to be to each other before any noticeable (measurable) interference actually occurred (and before any of the alarms on the ESU's started sounding). A bit of "RF blending" of the waveforms - and therefore possible unexpected results at the sharp end - would be my guess (especially if the ESU's were being used in different modes). Would anyone (the surgeons, for example) notice? And, if they did (and become worried by it all), why not simply take it in turns to "blaze away"!
Anyway, there's a nice little PhD project for someone there!
